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By Richard Jr. Ray, Richard Druesedow

The Virginia Operations of Consolidation Coal Co. include a diversity of mine fan configurations which have been tested to quantify pressure losses through the inlet ductwork. Airflow and pressure measurements were taken at four shaft sites to calculate losses for the 90-degree bend at the top of the shaft and the self-closing dampers or closing doors located between the shaft and fan. Velocity contours were then developed from the test data to determine flow patterns in each fan system component. In addition, yaw and pitch angles of airflow through the fan annulus were measured to evaluate turbulence levels created by various inlet ductwork designs. The test results indicate that proper design of the shaft collar and ductwork arrangement for main mine fans can substantially reduce system pressure losses and air turbulence. BY minimizing the pressure drop experienced on the surface, these design improvements enable the bulk of the total pressure developed by the fan(s) to be utilized in the mine.

Jan 1, 1995

By J. Scott McDougall, J. Herman P. Eng. Vanderlaag

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. The optimum warning alarm must be fast and able to reach all miners, regardless of their location or work activity. Current means of fire warning are varied, and include such methods as stench, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. A novel fire warning alarm which enables instantaneous warning of all underground personnel, the Canary Nine Messenger System, has been developed by VLF Magnetic Systems Inc. in conjunction with Noranda Technology Centre and the U.S. Department of the Interior - Bureau of Nines. The warning is sent by an electromagnetic signal which penetrates through mine rock to receivers housed in the battery packs which also power each miner's cap lamp. A loud buzzer in the integrated battery/receiver unit and the flashing of the cap lamp alerts miners to incoming messages. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This report describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, and the design of recently available transmitter and receivers.

Jan 1, 1995

By W. M. Schafer, C. F. Luckay, D. A. King

Monitoring devices have been installed at several mine sites to assess the potential for the development of acid rock drainage (ARD) in waste rock, spent ore and tailings material. In addition, instrumentation has been designed for monitoring changes in water quality in pit lakes. These devices monitor temperature, oxygen, water movement and water chemistry in the waste rock pile. This information can be used to evaluate the current and future ARD risks and the effectiveness of caps and covers. The information can also be used in the design of other reclamation strategies that limit ARD development. The instrumentation includes nested thermistors and oxygen sensing ports, neutron access tubes, heat dissipation units (HDUs) and lysimeters. Many of the monitoring devices can be linked to a data logger and telemetry systems, enabling monitoring data to be downloaded from the office.

Jan 1, 1999

By S. I. Nozhko, V. N. Guliy, A. A. Zolotarev, L. M. Luyshnia

The study of the apatite deposits of the Aldan Shield shows wide spread of the Precambrian apatite-carbonate ores and possibilities of using them for extraction of apatite. Dependency of flotation on ore minerals was studied according to the following scheme: preparation of the monomineralic samples of anhydrite, gypsum, chlorite, serpentine, phlogopite, apatite; mixing them in apatite ore of the average composition; followed by flotation. Another series of the experiments was conducted to ascertain a dependence of flotation activity of the different minerals on the different flotation reagents, which were used as collectors. It has been shown that apatite from silicate-carbonate ores is most extractable because it has the biggest size of grains and is the most free of inclusions. Beneficiation of the sulphate-containing apatite-carbonate rocks is possible when flotol - 7.9 is used as a collector. Meanwhile, the use of the tallaktam leads to an increase in the sulphate recovery. The estimation of individual technological features of the layered Mghydrosilicates and their influence on the process of beneficiation has been examined using samples of apatite-dolomite ore (P205-8%) with the addition of the phlogopite, serpentine and chlorite. The results show that there is little influence of the chlorite presence on the flotation while the serpentine presence leads to a decrease of the flotation, because of its high specific surface area.

Jan 1, 1993

By L. Shevenell

Nevada now has, or will have, 35 pit lakes resulting from open-pit mining below the water table. State regulators are requiring that the ultimate pit lake water quality be predicted as part of the permit application process. Water balances/pit lake filling rates must be esti¬mated in support of the geochemical modeling. In Nevada, analytical and numerical methods have been employed for the study of pit lakes. In the current work, analytical solutions are investigated for one pit lake, the Getchell south pit lake, which previously filled be¬tween 1968 and 1982 during a hiatus in mining. Water levels vs. time are available for this lake and these data have been fitted with a hyperbolic curve. This water-level-vs.-time curve was used in simple water-balance computations to find the net inflow rates by forcing computed water levels and volumes to match those of the known water levels and volumes through time. The model described here provides realistic volume fluxes into and out of the lake on a monthly basis as the pit lake filled.

Jan 1, 2000

The stability of mine roofs in permafrost zones is determined mainly by temperature and ice content. The deformation resulting from creep and temperature-dependent physical properties of frozen rock mass is the dominant component of total deformation. Roof bolts can consolidate the roof and control its deformation. In this paper, a finite-element model, for the analysis of the effects of roof bolting in a frozen rock mass is presented. The model includes the variables normally encountered when analyzing the effects of roof bolting in rocks. It also accounts for properties unique to frozen rock mass: creep deformation and the change in Young's modulus with changing temperature. The model shows that, as bolt spacing decreases, there is a trade-off between increased roof stability from increased mechanical support and decreased stability from increased conduction of heat into the frozen roof. This result was expected and shows that, for a given set of rock-mass conditions, including ice content, temperature, particle size, etc., there is an optimum bolt length and bolt density for minimum roof deflection.

Jan 1, 1997

By Karl Kuhnhenn

One substantial element of the NATM is to take into consideration the geotechnical rock behavior in the design of excavation and support methods. Even if this opinion is being shared increasingly, the stress analysis is not the sole criterion for a successful tunnel drive. By the beginning, the inventors of the NATM have clearly defined a number of principles which have kept their validity until now. The evaluation of different failure cases demonstrate how necessary the observance of these principles and their strict following during execution are besides the stress analysis. The great number of successfully excavated NATM tunnels are an impressive evidence for these principles.

Jan 1, 1995

By Ernest Selig, John Dunnicliff, Delon Hampton

This paper provides a summary of a two-day conference held in New Orleans in March 1980, entitled "Tunnel Instrumentation: Benefits and Implementation." The conference addressed two major questions: First, what are the benefits of using instrumentation during tunnel construction? Second, what contractual relations should be established for conducting instrumentation programs during tunnel construction? Each session consisted of brief formal presentations and extensive panel discussions with participation from attendees. Attendees included owners, designers, contractors, and instrumentation specialists. This paper presents a consensus of views expressed during the conference.

Jan 1, 1981

By R. D. Beard

Puerto Rico lies within the remnants of a deformed Cretaceous island arc system in the northeastern Caribbean. The Island can be divided into three broad geologic provinces: the Central Volcanic-Plutonic Province (Lower Cretaceous to middle Eocene), and the Northern and Southern Limestone Provinces (early Oligocene to middle Miocene). Known precious metal deposits are generally small and occur in veins and shear zones within Lower and Upper Cretaceous volcanic and plutonic rocks. Some Tertiary igneous rocks are also mineralized. Selected indications of disseminated lithology-controlled mineralization could represent larger deposits. Associated metals in some deposits include copper, zinc, and lead. At present, tax policies, population density, political outlook, and lack of proven significant precious metal deposits discourage the establishment of a metal mining industry.

Jan 1, 1993

By J. Koinig, K. Mussger, St. Reischl

Jet grouting is a viable supplementary measure for NATM tunneling in special softground conditions. In particular it is used as a type of forepoling to maintain face stability and to provide initial support for large openings until the shotcrete lining reaches sufficient strength. For this purpose cement grout is injected under high pressure through horizontal pipes outside of the tunnel perimeter and thoroughly mixed with the soil producing 1 to 3-foot diameter cylindrical beams. Excavation of the tunnel then proceeds beneath this umbrella of 40 to 50 foot long beams. Design and construction experiences from recent projects are presented for tunnels diameters between 30 and 50 feet in fill and alluvial and colluvial deposits.

Jan 1, 1987

By D. E. Ranta, John G. Stone

One of the steps in an ore reserve estimate is customarily a rigorous calculation of the in situ grade of the orebody itself. The result of this calculation is usually reduced by some purely arbitrary factor to force the calculation to agree with the observed grade of ore actually mined. The failure of the calculation to realistically depict the grade of ore actually extracted is in many instances not the result of either an incorrect calculation procedure or of sloppy mining practice, but is a direct consequence of unsuspected irregularities in the contact between the orebody and the surrounding wall rock. A pattern of holes spaced at 1.5-3.Om foot intervals, drilled as part of a pre-development program, will often reveal that a presumed "regular' ore/waste contact is, in fact, so highly irregular that it will be next to impossible to separate ore from waste during mining. In such an instance, 'fingers' of waste projecting into the mining block will substitute for equal volumes of ore left outside the mining limits. As a result, the grade of material actually mined will be less than the grade envisioned for the orebody. The volume of waste substituting for ore in the mining block is about 0.4X, where X = the average error in projecting the ore/waste contact between alternate holes in the test pattern, and is expressed in units of volume per unit of area of the contact surface.

Jan 1, 1992

During 1997-2001, an EC funded project investigated the environmental consequences of the use of industrial waste and sewage sludge based artificial top soils (ATS) in rehabilitating large coalmine waste dumps in the Saar region of Germany. Both the laboratory leaching tests and field lysimeter data analysis carried out by the research partners have shown that the amount of dissolved heavy metals in the leachate was low, and generally below the regulatory limits. However, the dissolved amount of nutrients, especially mineral nitrogen, was found to be relatively high. The hydrological properties of waste rocks and ATS mixtures were established through history matching of the laboratory column tests and the field measurements. 1D column models and 3D field models were used to numerically simulate pollutant transport at the ATS rehabilitated waste dumps. This paper presents the findings of the numerical modelling research carried out for the characterisation of hydrological and pollutant transport properties of rehabilitated coalmine waste dumps in the Saar coalfield.

Jan 1, 2003

By Paul Saxton

INTRODUCTION AND SUMMARY This short paper deals with the history of the Nickel Plate Mine from 1898 to 1987, with the major focus on the time period 1984 to 1987. Operations from 1898 to 1955 are reviewed in a cursory manner with the emphasis on some interesting points in the early 20th century. A review of the major exploration work carried out in 1984 to 1987 is presented and the process of moving the project through feasibility, government permitting and construction is described. The Hedley gold camp is situated approximately 40 kilometres east-southeast of Princeton, in southern British Columbia. The area has had a long history of gold mining and between 1902 and 1955 approximately 1.5 million ounces of gold were won from several mineralized skarn orebodies. Most production came from the Nickel Plate and Hedley Mascot mines. AN EARLY TO MID 20TH CENTURY SUMMARY The Nickel Plate is one of the oldest mines in the province. The mine had operated from 1904 to 1930 and, after a period of shutdown, from 1934 to 1955. The mine was revived in 1967 for exploration and. will resume production during the first half of 1987. In the first period the Yale Mining Company and Daly Reduction Company operated for six years and Hedley Gold Mining Company for twenty-one. In the second period the mine was operated by the Kelowna Exploration Company Limited and Kelowna Mines Hedley Limited for twenty-one years. In the present period the mine has been revived by Mascot Gold Mines Limited.

Jan 1, 1987

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By R. V. Ramani, K. V. K. Prasad

Forecasting mined grade variability from exploration information is a challenging task in mine planning. For effective planning of activities, such as workplace scheduling, ore grade quality control, etc., development of realistic numerical simulation models of in situ variability from exploration information is an essential first step. Geostatistical conditional simulation (GCS) is one of the well known methods to develop such simulations. Recently, stochastic fractal models based on the assumptions of scale-invariance and self-similarity have been used for developing simulations of several natural phenomena. It has been suggested that these models might permit the generation of short-scale variability information from exploration data with greater fidelity when the data satisfies the attendant assumptions. In this paper, stochastic fractal models are reviewed, and their relationship to geostatistical variogram models is examined. A comparison of the two simulation techniques has been performed using coal sulfur data from a mined-out coal property. The results of this comparative analysis are also presented in the paper.

Jan 1, 1993

By V. B. Achanti, A. W. Khair

This paper deals with the effects of various bit geometric parameters on the failure characteristics of rock material. Improving the rock-cutting efficiency of continuous mining machines has proven to be an interesting research topic during the last few decades. In the current study, an automated rotary rock-cutting simulator, duplicating a continuous miner, was used to study these parameters in the laboratory. The improvement of bit performance in terms of its life, cutting efficiency, dust production and energy consumption has drawn widespread attention. Research has demonstrated that optimizing bit parameters can result in efficient fragmentation of rock. Indiana limestone rock material was used in this study. The bit tip angle, bit tip size, bit spacing, depth of cut and cutting velocity of the rotary drum were varied to investigate the failure characteristics. The cutting pressure, penetrating pressure and the depth of cut were monitored on the simulator during the cutting process. Airborne dust and settled dust were measured for each experiment. Then, the specific airborne dust and specific energy were determined for each type of bit. Triaxial tests were carried out to correlate the failure angle of the rock in the static case to the dynamic cutting process failure. The physical and mechanical properties of the rock were also determined to assess their influence on the wear characteristics of each bit.

Jan 1, 2000

By Shallesh K. Patel, Richard M. Powers, Patrick Zhang

Perceived environmental impacts from flotation reagents used in the phosphate industry have been of concern for nearly a decade. A research program was initiated to determine the distribution, fate, and consequences of flotation reagents (fatty acids, fuel oils, and amines) within the environment. Therefore, laboratory investigations of biodegradation and soil attenuation of the reagents were conducted along with field flotation mass balances and groundwater investigations in clay settling, sand tailings, and undisturbed areas. Sample analysis and a reagent mass-balance model indicated that most reagents are distributed in clay settling and sand tailings areas. Groundwater analyses showed no fatty acids or amines in any of 19 surficial or intermediate aquifer water samples. In contrast, fuel oils were detected in the surficial aquifer at all sand tailings areas in concentrations ranging between 8.5 and 0.5 mg/L. Fuel oil was also detected in trace amounts (0.6 mg/L) in one intermediate aquifer well located in an active sand tailings area. All fuel oil concentrations detected were very low and, coupled with a biodegradation rate of approximately 10% per month, all concentrations should be within reference levels in six months. Based upon the results of this study, use of flotation reagents in the beneficiation process of the Florida phosphate industry present no long-term threat to the environment.

Jan 1, 1999

By G. T. Lineberry, B. R. Yama

Artificial intelligence research has produced several tools for commercial application. Some of the techniques that are widely used today include neural networks, fuzzy logic and expert systems. Artificial neural networks (ANNs) are excellent predictive, pattern recognition and data analysis tools. In the mining industry, ANN techniques are being used commercially for real-time process-control applications. Modeling of spatial data, ore-reserve estimation, tunnel design, long wall-stability prediction and geologic roof classification are additional applications in which neural networks have been applied successfully. In this study, a standard back propagation algorithm was used to train a series of neural networks for a real-world predictive task. After training and optimizing the neural network architecture, the performance of the network is measured on an independent validation set. Results indicate a mean error of less than 1 % between the actual and predicted values. A neural network model was developed for learning the spatial continuity of a mineral field and, consequently, for predicting sulfur values for given coordinates. The neural network not only performed satisfactorily, but in some cases performed even better than the kriging model.

Jan 1, 2000

By J. Twining, V. Nguyen, J. Perera

A computer code for ecological risk assessment (ERA), AQUARISK, has been developed and applied to evaluate the likelihood of biotic detriment due to exposure to acid rock drainage (ARD) from the Burkunga mine site in Australia Stream water quality monitoring data were used for the assessment and were compared with a) national water quality guidelines, b) literature derived ecotoxicology data and c) biological monitoring data. With bioavailability calculations, the code predicted that, for metals exceeding the guidelines, 44% of macroinvertebrate species above the mine and 100% below the mine would be adversely affected by the metals in the stream. This compares reasonably and conservatively with biological monitoring that showed observed reductions of 41% and 85% of species respectively at each site. Using literature data for macroinvertebrates to predict impact produced similar estimates to using data for all taxa. Use of speciation modeling also lessened the degree of reduction in the median water metal concentrations required to achieve acceptable impact (measured either by exceedence of criteria or by species likely to be affected) by a factor of 75%. This result implies significant economic and management benefits in relation to remedial engineering or water treatment options for sites.

Jan 1, 2000

By R. L. Wiegel

Several mineral process modeling and simulation packages are currently available for use in evaluating the performance of alternative process flow schemes. A critical link that has been missing from these packages is the ability to quantitatively model the effect of size reduction on the liberation of the valuable and waste minerals in the ore being processed. Although there have been several approaches taken to this problem over the past 25 years, none of them has led to a satisfactory conclusion. A technique was developed for measuring the effective liberation characteristics of magnetic taconite ores, and a program was constructed that makes use of these liberation characteristics in simultaneously simulating both size reduction and mineral liberation as it occurs in tumbling mills. This is an especially important step in the modeling of magnetic taconite processes, where magnetic rejection of low-grade wastes between grinding stages mandates that a predictive capability be available. The current application is specific to magnetic taconite, but it is possible that a similar approach could be used for other types of mineral systems. Key words: Modeling and simulation, Size reduction, Mineral liberation, Taconite, Magnetic concentrator

Jan 1, 2003